Spiders

"'Follow the spiders.' I'll never forgive Hagrid. We're lucky to be alive."
-- Ron Weasley, after an evening jaunt in the Forest (CS15)

Spiders are arachnids, eight-legged creatures similar to insects. Hogwarts castle has quite a few common spiders, as do most human habitations. Magical spiders, unlike their common relatives, can be quite large and terrifying. The acromantula, a gigantic arachnid native to Borneo, is the best known of the magical spiders (FB, CS15, GF31, OP16).

The fake Moody used three spiders to demonstrate the Unforgivable Curses (GF14).

Ron Weasley's greatest fear is spiders, ever since the twins turned his teddy bear into a giant spider when he was little. He can work with dead spiders as potion ingredients without difficulty, however (CS9, PA7).